Developing nanostructured cathode of thin film SOFC and its characteristics

摘要

Thin film Solid Oxide Fuel Cells (TFSOFC) have been intensively researched because of their potentials in compact and high-efficiency energy conversion applications. It was found that the microstructural variations in the electrolyte and electrode could affect the reaction kinetics of TFSOFCs dramatically. In this paper we present a study of the effects of nanostructured cathodes on their electrochemical performance. Nanostructured thin film cathodes were processed using a pulsed laser deposition technique (PLD). Using PLD we were able to process vertically aligned nanopores in cathode structures with enhanced oxygen-gas phase diffusivity, thus improving TFSOFCs performance. La0.5Sr0.5CoO3 (LSCO), La1??xSrxCo0.8Fe0.2O3 (LSCFO) and other cathode materials were deposited on various substrates (YSZ, Si and pressed Ce0.9Gd0.1O1.95 disks). Microstructures and properties of the nanostructured cathodes were characterized by XRD, TEM, HRTEM, SEM and electrochemical meas! urements. We explored the oxygen-gas phase diffusion efficiency as a function of nanopore size using electrochemical impedance spectroscopy. We also investigated the thermal stress built in the cell as a function of nanopore sizes. These well-aligned nanopores could not only relieve or partially relieve the internal thermal stress and lattice strain caused by the differences of thermal expansion coefficients and lattice mismatch between the electrode and electrolyte but also facilitate the oxygen diffusion through the cathode electrode.